Substance P immunoreactivity exhibits sexual dimorphism and colocalization with neurokinin B in the human infundibular nucleus

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 515-547-Female Reproductive Endocrinology
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-540
Erik Hrabovszky*1, Beáta Á. Borsay2, Kálmán Rácz2, László Herczeg2, Philippe Ciofi3, Stephen R Bloom4, Mohammad A Ghatei4, Waljit Singh Dhillo4 and Zsolt Liposits1
1Institute of Experimental Medicine, Budapest, Hungary, 2Faculty of Medicine of the University of Debrecen, Debrecen, Hungary, 3INSERM U862, Neurocentre Magendie, Bordeaux, France, 4Imperial College London, London, United Kingdom
Neurons synthesizing neurokinin B in the hypothalamic arcuate nucleus of laboratory species are important upstream regulators of pulsatile gonadotropin-releasing hormone neurosecretion. The analogous neurons of the human infundibular nucleus (Inf) appear to exhibit several distinct neurochemical characteristics. In search of neuropeptides co-expressed in these cells, we have carried out a series of immunohistochemical studies in autopsy samples obtained from men of various ages and postmenopausal women.

In histological specimens processed with peroxidase-immunolabeling, the Inf contained a very dense fiber network immunoreactive to the preprotachykinin A gene product substance P. Quantitative analysis of the lightly-stained cell bodies established a sex difference and identified higher density of labeled perikarya in the Inf of postmenopausal women, compared with age-matched men. Dual-immunofluorescent studies provided evidence for substance P immunoreactivity in a large subset of neurokinin B-immunoreactive axons. In contrast, neurokinin B-immunoreactive axons in the Inf tended not to contain immunoreactive galanin and only rarely contained immunoreactive dynorphin, unlike neurokinin B-immunoreactive axons in the mouse arcuate nucleus. The absence of galanin, infrequent occurrence of dynorphin and frequent expression of substance P immunoreactivity in neurokinin B-immunoreactive fibers in the human Inf represent conspicuous species differences from the mouse and exemplifies the inherent limitations of the rodent models for human reproduction. The functional significance of substance P/neurokinin B colocalization in the human Inf requires clarification.

Nothing to Disclose: EH, BB, KR, LH, PC, SRB, MAG, WSD, ZL

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Sources of Research Support: Supported by the National Science Foundation of Hungary (OTKA K83710, K100722) and the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n°245009.